Power Semiconductor Package with Non-Contiguous, Multi-Section Conductive Carrier

ABSTRACT

In one implementation, a power semiconductor package includes a non-contiguous, multi-section conductive carrier. A control transistor with a control transistor terminal is coupled to a first section of the multi-section conductive carrier, while a sync transistor with a sync transistor terminal is coupled to a second section of the multi-section conductive carrier. The first and second sections of the multi-section conductive carrier sink heat generated by the control and sync transistors. The first and second sections of the multi-section conductive carrier are electrically connected only through a mounting surface attached to the power semiconductor package. Another implementation of the power semiconductor package includes a driver IC coupled to a third section of the multi-section conductive carrier. A method for fabricating the power semiconductor package is also disclosed. The power semiconductor package according to the present disclosure results in effective thermal protection, current carrying capability, and a relatively small size.

The present application claims the benefit of and priority to aprovisional application entitled “Semiconductor Package Including AConductive Carrier Embedded Power Switching Stage,” Ser. No. 61/901,987filed on Nov. 8, 2013. The disclosure in this provisional application ishereby incorporated fully by reference into the present application.

The present application is also continuation-in-part of application Ser.No. 14/022,584, filed on Sep. 10, 2013, which in turn claims priority toprovisional application Ser. No. 61/715,737, filed on Oct. 18, 2012. Thedisclosures in these applications are hereby incorporated fully byreference into the present application. The present application claimspriority to these earlier filed applications.

BACKGROUND Background Art

Semiconductor packages used in power applications employ powertransistors, and are required to operate under high voltage andpotentially high temperature conditions. For example, power transistorsin voltage converters, sometimes referred to as control and synctransistors, generate substantial heat during operation. The potentiallydamaging heat can be diverted away from control and sync transistorsusing a heat spreader, which is often relatively large. In addition, theconnection between the control transistor and the sync transistorprovides a switch node and is typically implemented using a conductiveclip, such as a copper clip, which must be sufficiently robust toaccommodate high current. Moreover, because the control and synctransistors can be very sensitive to electrical resistance, thecross-sectional area of the conductive clip used to provide the switchnode need be relatively large.

Consequently, packages in power applications, such as voltage converterpower semiconductor packages, must typically be sized to accommodate notonly control and sync transistors, but a large heat spreader providingthermal protection for those power transistors, and a large conductiveclip for their connection, as well. Using heat spreaders and conductiveclips require much additional space, and significantly increase the sizeof power semiconductor packages.

SUMMARY

The present disclosure is directed to a power semiconductor package withnon-contiguous, multi-section conductive carrier, substantially as shownin and/or described in connection with at least one of the figures, andas set forth more completely in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of an exemplary circuit suitable for use as avoltage converter.

FIG. 2 shows an exemplary representation of a packaging solutionaccording to one implementation of the present disclosure.

FIG. 3 shows a flowchart presenting an exemplary method for fabricatinga semiconductor package according to one implementation of the presentdisclosure.

FIG. 4A illustrates a result of performing of an initial actionaccording to the flowchart of FIG. 3 in accordance with oneimplementation of the present disclosure.

FIG. 4B illustrates a result of performing of a subsequent actionaccording to the flowchart of FIG. 3 in accordance with oneimplementation of the present disclosure.

FIG. 4C illustrates a result of performing of a subsequent actionaccording to the flowchart of FIG. 3 in accordance with oneimplementation of the present disclosure.

FIG. 4D illustrates a result of performing of a subsequent actionaccording to the flowchart of FIG. 3 in accordance with oneimplementation of the present disclosure.

FIG. 4E illustrates a result of performing of a subsequent actionaccording to the flowchart of FIG. 3 in accordance with oneimplementation of the present disclosure.

FIG. 4F illustrates a result of performing of a final action accordingto the flowchart of FIG. 3 in accordance with one implementation of thepresent disclosure.

FIG. 5 shows an exemplary representation of a packaging solutionaccording to another implementation of the present disclosure.

DETAILED DESCRIPTION

The following description contains specific information pertaining toimplementations in the present disclosure. One skilled in the art willrecognize that the present disclosure may be implemented in a mannerdifferent from that specifically discussed herein. The drawings in thepresent application and their accompanying detailed description aredirected to merely exemplary implementations. Unless noted otherwise,like or corresponding elements among the figures may be indicated bylike or corresponding reference numerals. Moreover, the drawings andillustrations in the present application are generally not to scale, andare not intended to correspond to actual relative dimensions.

Power converters, such as voltage regulators, are used in a variety ofelectronic circuits and systems. For instance, integrated circuit (IC)applications may require conversion of a direct current (DC) input to alower, or higher, DC output. As a specific example, a buck converter maybe implemented as a voltage regulator to convert a higher voltage DCinput to a lower voltage DC output for use in low voltage applicationsin which relatively large output currents are required.

FIG. 1 shows a diagram of an exemplary circuit suitable for use as avoltage converter. Voltage converter 100 includes voltage convertermulti-chip module (MCM) 102, output inductor 104, and output capacitor106. As shown in FIG. 1, MCM 102 includes power switching stage 101 ofvoltage converter 100, and driver IC 194 implemented to provide drivesignals to power switching stage 101. As shown in FIG. 1, voltageconverter 100 is configured to receive an input voltage V_(IN), and toprovide a converted voltage, e.g., a rectified and/or stepped downvoltage, as V_(OUT) at output 105.

Power switching stage 101 may be implemented using two power switches inthe form of metal-oxide-semiconductor field-effect transistors (MOSFETs)configured as a half bridge, for example. That is to say, powerswitching stage 101 may include high side or control switch 120 (Q₁)having drain 122, source 124, and gate 126, as well as low side or syncswitch 130 (Q₂) having drain 132, source 134, and gate 136. Controlswitch 120 is coupled to sync switch 130 at switch node 129, which, inturn, is coupled to output 105 through output inductor 104. Respectivecontrol and sync switches 120 and 130 may be implemented as group IVbased power transistors, such as silicon power MOSFETs having a verticaldesign, for example. Voltage converter 100 may be advantageouslyutilized, for example as a buck converter, in a variety of automotive,industrial, appliance, and lighting applications.

It is noted that in the interests of ease and conciseness ofdescription, the present inventive principles will in some instances bedescribed by reference to specific implementations of a buck converterincluding one or more silicon based power FETs. However, it isemphasized that such implementations are merely exemplary, and theinventive principles disclosed herein are broadly applicable to a widerange of applications, including buck and boost converters, implementedusing other group IV material based, or group III-V semiconductor based,power transistors. It is noted that as used herein, the phrase “groupIII-V” refers to a compound semiconductor including at least one groupIII element and at least one group V element. By way of example, a groupIII-V semiconductor may take the form of a III-Nitride semiconductorthat includes nitrogen and at least one group III element. For instance,a III-Nitride power transistor may be fabricated using gallium nitride(GaN), in which the group III element or elements include some or asubstantial amount of gallium, but may also include other group IIIelements in addition to gallium.

Power switches such as control and sync switches 120 and 130 are capableof generating substantial heat during operation. The potentiallydamaging heat can be diverted away from control and sync switches 120and 130 using a heat spreader, which is often relatively large. Inaddition, the connection between control switch 120 and sync switch 130providing switch node 129 is typically implemented using a conductiveclip, such as a copper clip, which must be sufficiently robust toaccommodate high current. Moreover, because control switch 120 and syncswitch 130 can be highly sensitive to electrical resistance, thecross-sectional area of the conductive clip used to provide switch node129 may also be relatively large. Consequently, packaging solutions forpower switching stage 101 and/or MCM 102 must typically be sized toaccommodate not only control and sync switches 120 and 130, but a largeheat spreader providing thermal protection for those power switches, anda large conductive clip for their connection, as well.

The present application discloses a packaging solution enabling omissionof the aforementioned heat spreader and switch node conductive clip,while concurrently providing thermal protection for control and syncswitches 120 and 130, and also providing a reliable, low resistance, andsubstantially parasitic free electrical connection for establishingswitch node 129. In one implementation, power switching stage 101 isembedded in a conductive carrier utilized as a structural support in thepackaging solution, such as a conductive lead frame for example, whichis configured to provide integrated heat spreading. In addition, thesupport structure used to provide the conductive carrier can also beused to provide switch node 129. FIG. 2 shows an exemplaryrepresentation of a packaging solution according to one implementationof the present disclosure.

FIG. 2 shows a cross-sectional view of semiconductor package 201attached to mounting surface 290, which may be a printed circuit board(PCB) for example, by solder bodies 292. Semiconductor package 201includes fully patterned or multi-section conductive carrier 210, whichitself includes conductive carrier sections 210 a, 210 b, 210 c, 210 d,and 210 e (hereinafter “conductive carrier sections 210 a-210 e”). Asshown in FIG. 2, the fully patterned or multi-section conductive carrier210 is a non-contiguous conductive carrier, and is made up of patternedand disjointed sections that are housed within semiconductor package201, and that are in electrical communication only through mountingsurface 290. As shown in FIG. 2, conductive carrier 210 has die side208, and opposite input/output (I/O) side 218 connecting semiconductorpackage 201 to mounting surface 290. The non-contiguous, fully patternedor multi-section conductive carrier 210, is also referred to simply as“conductive carrier” in the present application.

Semiconductor package 201 further includes control FET 220 (Q₁) havingdrain 222, source 224, and gate 226, as well as sync FET 230 (Q₂) havingdrain 232, source 234, and gate 236. Control FET 220 and sync FET 230are specific examples of power transistors used for illustrativepurposes in the present application. However, it is manifest that othertypes of power transistors can be used as well without departing fromthe scope of the present inventive concepts. Thus, control FET 220 maybe referred to as control transistor and sync FET 230 may be referred toas sync transistor in the present application. Source, drain, and gateof either control FET and/or sync FET may be referred to as a transistorterminal. A control transistor terminal may refer to source, drain, orgate of the control transistor, i.e. control FET 220 in the presentexample. Likewise, a sync transistor terminal may refer to source,drain, or gate of the sync transistor, i.e. sync FET 230 in the presentexample. Moreover, semiconductor package 201 may be referred to as a“power semiconductor package” in the present application.

As shown in FIG. 2, drain 222 of control FET 220 is attached to die side208 of conductive carrier section 210 b, and source 234 of sync FET 230is attached to die side 208 of conductive carrier section 210 d. Asfurther shown in FIG. 2, conductive carrier section 210 a includesconductive carrier buildup region 221 a, conductive carrier section 210c is attached to gate 236 of sync FET 230, and conductive carriersection 210 e includes conductive carrier buildup region 221 e. Inaddition, semiconductor package 201 includes electrically conductive dieattach material 219, patterned dielectric 240, and insulator layer 250providing surface 252.

Also included as part of semiconductor package 201 are drain contact 223provided by conductive carrier section 210 b, source contact 235provided by conductive carrier section 210 d, gate contacts 227 and 237provided by respective conductive carrier sections 210 a and 210 c, andswitch node contact 229 provided by conductive carrier section 210 e.Conductive carrier section 210 e is also referred to as a switch nodesection of the conductive carrier. It is noted that in addition toproviding drain contact 223, conductive carrier section 210 b isconfigured to sink heat produced by control FET 220 into mountingsurface 290. Moreover, in addition to providing source contact 235,conductive carrier section 210 d is configured to sink heat produced bysync FET 230 into mounting surface 290. It is further noted thatconductive carrier section 210 e is configured to provide switch nodecontact 229, as well as to provide integrated heat spreadingfunctionality for dissipation of heat generated by control and sync FETs220 and 230. In general, conductive carrier sections 210 a, 210 b, 210c, 210 d, and 210 e provide electrical contacts as well as integratedheat spreading by sinking heat produced by control FET 220 and sync FET230 into mounting surface 290.

Semiconductor package 201 corresponds in general to power switchingstage 101 in FIG. 1. In addition, control FET 220 having drain 222,source 224, and gate 226, and sync FET 230 having drain 232, source 234,and gate 236, correspond in general to control switch 120 having drain122, source 124, and gate 126, and sync switch 130 having drain 132,source 134, and gate 136, respectively, in FIG. 1. Moreover, switch nodecontact 229, in FIG. 2, corresponds to switch node 129, in FIG. 1.

The features of semiconductor package 201 will be described in greaterdetail by reference to FIG. 3, and FIGS. 4A, 4B, 4C, 4D, 4E, and 4F(hereinafter “FIGS. 4A-4F”). However, it is noted in reference to FIG. 2that the electrical connection between source 224 of control FET 220 anddrain 232 of sync FET 230 is established in the absence of a conductiveclip or other feature implemented solely or primarily as an electricalconnector. Instead, according to the implementation shown in FIG. 2, theelectrical connection between source 224 and drain 232 establishingswitch node contact 229 is advantageously provided by conductive carriersection 210 e, which includes conductive buildup region 221 e. As aresult, the packaging solution of FIG. 2 provides a robust, lowresistance, and low parasitic connection for providing switch nodecontact 229. Moreover, the inventive concepts disclosed by the packagingsolution represented in FIG. 2 can be extended to enable the fabricationof high density MCM packages, with reduced parasitics and improvedthermal performance.

Referring to FIG. 3, FIG. 3 shows flowchart 300 presenting an exemplarymethod for fabricating a semiconductor package according to oneimplementation of the present disclosure. It is noted that the methoddescribed by flowchart 300 is performed on a portion of a conductivecarrier structure, which may be a semiconductor package lead frame, ormay take the form of a conductive sheet or plate, for example.

With respect to FIGS. 4A-4F, structures 410 through 415 shownrespectively in those figures illustrate the result of performing themethod of flowchart 300 according to one implementation of the presentdisclosure. For example, FIG. 4A represents non-contiguous,multi-section conductive carrier 410 including conductive carriersections 410 a, 410 b, 410 c, 410 d, and 410 e (hereinafter “conductivecarrier sections 410 a-410 e”) having die side 408 and opposite I/O side418 (action 310), structure 411 shows non-contiguous, multi-sectionconductive carrier 410 after attachment to a control FET and a sync FET(action 311), structure 412 shows structure 411 after the formation of adielectric layer (action 312), and so forth. It is noted thatnon-contiguous, multi-section conductive carrier 410 includingconductive carrier sections 410 a-410 e, in FIGS. 4A through 4F,corresponds to conductive carrier 210 including conductive carriersections 210 a-210 e, in FIG. 2.

Referring to flowchart 300, in FIG. 3, in combination with FIG. 4A,flowchart 300 begins with fabricating and/or providing a non-contiguous,multi-section conductive carrier 410 including conductive carriersections 410 a-410 e and having die side 408 and opposite I/O side 418(action 310). As shown in FIG. 4A, non-contiguous, multi-sectionconductive carrier 410 is represented as a pre-patterned conductivesheet or plate having die side 408, I/O side 418, and gaps 409 a, 409 b,409 c, and 409 d (hereinafter “gaps 409 a-409 d”) pre-patterned betweenrespective conductive carrier sections 410 a-410 e and extending throughthe entire thickness of the conductive carrier between die side 408 toI/O side 418.

It is noted that conductive carrier sections 410 a-410 e are shown asconnected by dashed lines 416 to indicate that gaps 409 a-409 d may bevisible in FIGS. 4A-4F due to the cross-sectional perspective viewed inthose figures, but do not extend through conductive carrier 410 in adirection perpendicular to the plane of the page of FIGS. 4A-4F. Thusnon-contiguous, multi-section conductive carrier 410 may be made from alead frame that is fully patterned to provide conductive carriersections 410 a-410 e. Fully patterned conductive carrier 410 may beformed of any conductive material having a suitably low electricalresistance. Examples of materials from which fully patterned,non-contiguous, multi-section conductive carrier 410 may be formedinclude copper (Cu), aluminum (Al), or a conductive alloy. In oneimplementation, as noted above, fully patterned conductive carrier 410may be implemented using a semiconductor package lead frame.

Although the present exemplary implementation shows non-contiguous,multi-section conductive carrier 410 as including gaps 409 a-409 d, inother implementations, non-contiguous, multi-section conductive carrier410 may have more, or fewer, gaps than gaps 409 a-409 d. Moreover,although not shown in the present figures, in some implementations,non-contiguous, multi-section conductive carrier 410 may include abarrier metal layer formed on one or both of die side 408 and I/O side418. Such a barrier metal layer may be formed of nickel-gold (NiAu) ornickel-palladium-gold (NiPdAu), for example. In some implementations,such a barrier metal layer may serve as an etching mask duringpatterning of non-contiguous, multi-section conductive carrier 410.Thereafter, such a barrier metal layer can provide a solderable surfaceat one or both of die side 408 and I/O side 418 of non-contiguous,multi-section conductive carrier 410.

Moving to structure 411 in FIG. 4B with ongoing reference to FIG. 3,flowchart 300 continues with attaching control FET 420 (Q₁) and sync FET430 (Q₂) to non-contiguous, multi-section conductive carrier 410 (action311). Control FET 420 includes drain 422, source 424, and gate 426,while sync FET 430 includes drain 432, source 434, and gate 436. Asshown in FIG. 4B, control FET 420 and sync FET 430 are attached to dieside 408 of non-contiguous, multi-section conductive carrier 410 byelectrically conductive die attach material 419.

Electrically conductive die attach material 419 may be any suitablesubstance, such as a conductive epoxy, solder, a conductive sinteredmaterial, or a diffusion bonded material, formed to a thickness of atleast 10 μm, for example. Control FET 420 and sync FET 430 are shown aspower FETs having a vertical topology. That is to say, source 424 andgate 426 are situated on the same side of control FET 420, while drain422 is situated on an opposite side of control FET 420. Similarly,source 434 and gate 436 are situated on the same side of sync FET 430,while drain 432 is situated on an opposite side of sync FET 430.

In one implementation, respective control and sync FETs 420 and 430 maytake the form of group IV material based vertical FETs, such as siliconvertical MOSFETs for example. However, in other implementations,respective control and sync FETs 420 and 430 may take the form of groupIII-V based power FETs, such as GaN or other III-Nitride based FETs.

It is noted that control FET 420 and sync FET 430 are flipped relativeto each other. That is to say, control FET 420 is disposed onnon-contiguous, multi-section conductive carrier 410 in a “face up”orientation in which drain 422 is attached to die side 408 of conductivecarrier section 410 b, while sync FET 430 is oriented “face down” suchthat gate 436 and source 434 are attached to die side 408 of respectiveconductive carrier sections 410 c and 410 d. Moreover, and as shown inFIG. 4B, sync FET 430 is disposed over gap 409 c such that gap 409 c issituated between the attachment of source 434 to die side 408 ofconductive carrier section 410 d and the attachment of gate 436 to dieside 408 of conductive carrier section 410 c. Control FET 420, sync FET430, and electrically conductive die attach material 419 correspondrespectively to control FET 220, sync FET 230, and electricallyconductive die attach material 219, in FIG. 2.

As shown by structure 412 in FIG. 4C, flowchart 300 continues withforming dielectric layer 438 over non-contiguous, multi-sectionconductive carrier 410, control FET 420, and sync FET 430 (action 312).As shown in FIG. 4C, in one implementation, dielectric layer 438 may beformed at die side 408 and I/O side 418 of non-contiguous, multi-sectionconductive carrier 410. Formation of dielectric layer 438 may beperformed through lamination of a pre-formed dielectric layer onto I/Oside 418 and/or die side 408 of non-contiguous, multi-section conductivecarrier 410, control FET 420, and sync FET 430. Such a pre-formeddielectric layer may be cut or otherwise separated from a pre-formabledielectric material, for example an epoxy-phenolic or cyanateester-epoxy build-up material or any other pre-formable dielectricutilized in laminate substrate technology. In one implementation,dielectric layer 438 may be formed of a B-stage polymeric material curedduring lamination. As a result, and as shown in FIG. 4C, dielectriclayer 438 can substantially fill gaps 409 a-409 d appearing in FIGS. 4Aand 4B.

Referring to FIG. 4D, flowchart 300 continues with patterning ofdielectric layer 438 to form patterned dielectric 440 (action 313).Patterned dielectric 440 may be produced so as to provide windows 442.Patterning of dielectric layer 438 to form patterned dielectric 440including windows 442 can be performed using any known technique, suchas laser or mechanical drilling, for example. Patterned dielectric 440includes windows 442 exposing portions of die side 408 of conductivecarrier sections 410 a and 410 e, as well as exposing source 424 andgate 426 of control FET 420, and drain 432 of sync FET 430. In addition,according to the exemplary implementation shown in FIG. 4D, patterningof dielectric layer 438 to produce patterned dielectric 440 results inremoval of dielectric material from I/O side 418 of non-contiguous,multi-section conductive carrier 410. Patterned dielectric 440corresponds to patterned dielectric 240, in FIG. 2.

Moving to structure 414 in FIG. 4E, flowchart 300 continues withfabrication of one or more conductive layers over patterned dielectric440, and patterning of the conductive layer(s) to form conductivecarrier buildup regions 421 a and 421 e (action 314). The conductivelayer(s) may be formed of Cu or Al, for example, or may be formed from ametal alloy, such as a metal alloy including Cu and Ni, for example.Such conductive layer or layers may be built up using any suitabletechnique, such as electrochemical deposition or an electrolytic platingprocess, for example. After build up, the conductive layer or layers arepatterned to form conductive carrier buildup regions 421 a and 421 e.Conductive carrier buildup regions 421 a and 421 e correspondrespectively to conductive carrier buildup regions 221 a and 221 e, inFIG. 2.

It is noted that control FET 420 and sync PET 430 are substantiallyembedded in non-contiguous, multi-section conductive carrier 410including conductive carrier buildup regions 421 a and 421 e. As aresult, conductive carrier section 410 e including conductive carrierbuildup region 421 e can be utilized to electrically connect source 424of control FET 420 to drain 432 of sync FET 430. In addition, conductivecarrier section 410 e can be used to provide switch node contact 429.Moreover, patterned dielectric can 440 be utilized to provide electricalisolation of each of conductive carrier sections 410 a-410 e from theothers.

Continuing to structure 415 in FIG. 4F, flowchart 300 continues withforming insulator layer 450 over patterned dielectric 440 and conductivecarrier buildup regions 421 a and 421 e (action 315). Insulator layer450 may be formed as a blanket layer of solder resist, for example,which provides surface 452. Insulator layer 450 providing surface 452corresponds to insulator layer 250 providing surface 252, in FIG. 2.

Although the implementations shown and described by reference to FIGS.2, 3, and 4A-4F result in an MCM, such as semiconductor package 201, inFIG. 2, configured to enclose power switching stage 101, in FIG. 1, insome applications, it may be desirable to produce a semiconductorpackage corresponding to MCM 102. An example implementation of such anMCM package is shown by FIG. 5. One of ordinary skill in the art willreadily understand that the exemplary method outlined by flowchart 300,in FIG. 3, can be suitably adapted to produce the exemplary MCM packagestructure shown in FIG. 5.

FIG. 5 shows a cross-sectional view of semiconductor package 502attached to mounting surface 590, such as a PCB for example, by solderbodies 592. Semiconductor package 502 includes fully patterned ormulti-section conductive carrier 510 having die side 508 and oppositeI/O side 518, and including conductive carrier sections 510 a, 510 b,510 c, 510 d, 510 e, 510 f, and 510 g. As shown in FIG. 5, the fullypatterned or multi-section conductive carrier 510 is a non-contiguousconductive carrier, and is made up of patterned and disjointed sectionsthat are housed within semiconductor package 502, and that are inelectrical communication only through mounting surface 590. Thenon-contiguous, fully patterned or multi-section conductive carrier 510is also referred to simply as a “conductive carrier” in the presentapplication.

Semiconductor package 502 further includes control FET 520 (Q₁) havingdrain 522, source 524, and gate 526, as well as sync FET 530 (Q₂) havingdrain 532, source 534, and gate 536. Control FET 520 and sync FET 530are specific examples of power transistors used for illustrativepurposes in the present application. However, it is manifest that othertypes of power transistors can be used as well without departing fromthe scope of the present inventive concepts. Thus, control FET 520 maybe referred to as control transistor and sync FET 530 may be referred toas sync transistor in the present application. Source, drain, and gateof either control PET and/or sync FET may be referred to as a transistorterminal. A control transistor terminal may refer to source, drain, orgate of the control transistor, i.e. control FET 520 in the presentexample. Likewise, a sync transistor terminal may refer to source,drain, or gate of the sync transistor, i.e. sync FET 530 in the presentexample. Moreover, semiconductor package 502 may be referred to as a“power semiconductor package” in the present application.

As shown in FIG. 5, drain 522 of control FET 520 is attached to die side508 of conductive carrier section 510 b, and source 534 of sync FET 530is attached to die side 508 of conductive carrier section 510 d.Semiconductor package 502 also includes driver IC 594 for driving atleast one of control FET 520 and sync FET 530. In addition,semiconductor package 502 includes electrically conductive die attachmaterial 519, patterned dielectric 540, and insulator layer 550providing surface 552.

Also included as part of semiconductor package 502 are drain contact 523of control FET 520, source contact, 535 of sync FET 530, gate contacts527 and 537, switch node contact 529, I/O contacts 596 a and 596 b ofdriver IC 594, and die attach material 593 for attaching driver IC 594to conductive carrier section 510 f. It is noted that, depending on thedesired implementation, die attach material 593 may be an electricallyconductive die attach material or a dielectric die attach material.

Conductive carrier section 510 b, control FET 520, conductive carriersection 510 d, sync FET 530, conductive carrier sections 510 a, 510 c,and 510 e, and electrically conductive die attach material 519correspond respectively to conductive carrier section 210 b, control FET220, conductive carrier section 210 d, sync FET 230, conductive carriersections 210 a, 210 c, and 210 e, and electrically conductive die attachmaterial 219, in FIG. 2. In addition, patterned dielectric 540, contacts523, 527, 529, 535, and 537, and insulator layer 550, in FIG. 5,correspond respectively to patterned dielectric 240, contacts 223, 227,229, 235, and 237, and insulator layer 250, in FIG. 2. Moreover, it isnoted that semiconductor package 502 including driver IC 594, in FIG. 5,corresponds in general to MCM 102 including driver IC 194, in FIG. 1.

According to the implementation shown in FIG. 5, conductive carriersection 510 e advantageously provides switch node contact 529 andthereby establishes the electrical connection between source 524 ofcontrol FET 520 and drain 532 of sync FET 530. Conductive carriersection 510 e is also referred to as a switch node section of theconductive carrier. Patterned dielectric 540 can be used to protectdriver IC 594 from switching noise that may be present in conductivecarrier section 510 b, conductive carrier section 510 d, and conductivecarrier sections 510 a, 510 c, and 510 e by electrically isolating thoseconductive carrier sections from conductive carrier sections 510 f and510 g to which driver IC 594 is connected. In addition, patterneddielectric 540 can be used to electrically isolate conductive carriersections 510 a, 510 b, 510 c, 510 d, and 510 e from one another.Moreover, in addition to providing drain contact 523, gate contacts 527and 537, source contact 535, switch node contact 529, and I/O contacts596 a and 596 b, respective conductive carrier sections 510 b, 510 a,510 c, 510 d, 510 e, 510 f, and 510 g provide integrated heat spreadingby sinking heat produced by control FET 520, sync FET 530, and controlIC 594 into mounting surface 590.

Thus, embedding a power switching stage of a power converter in aconductive carrier utilized as a structural support in a semiconductorpackage advantageously enables a highly compact semiconductor packagedesign, while concurrently providing thermal protection. In addition, byembedding the power switching stage in the conductive carrier so as toutilize the conductive carrier to provide a switch node coupling acontrol switch to a sync switch, the present application enables furtherreductions in package size. For example, a package height, or thickness,resulting from the implementations disclosed in the present applicationmay be less than approximately 0.5 mm, such as a package height orthickness of approximately 0.45 mm. Furthermore, use of the conductivecarrier to provide the switch node advantageously enables omission of aconductive clip, or any other feature implemented solely or primarily asa switch node electrical connector, from the semiconductor package.

From the above description it is manifest that various techniques can beused for implementing the concepts described in the present applicationwithout departing from the scope of those concepts. Moreover, while theconcepts have been described with specific reference to certainimplementations, a person of ordinary skill in the art would recognizethat changes can be made in form and detail without departing from thescope of those concepts. As such, the described implementations are tobe considered in all respects as illustrative and not restrictive. Itshould also be understood that the present application is not limited tothe particular implementations described herein, but manyrearrangements, modifications, and substitutions are possible withoutdeparting from the scope of the present disclosure.

1. A power semiconductor package comprising: a non-contiguous,multi-section conductive carrier; a control transistor with a controltransistor terminal coupled to a first section of said multi-sectionconductive carrier; a sync transistor with a sync transistor terminalcoupled to a second section of said multi-section conductive carrier;said first and second sections of said multi-section conductive carriersinking heat generated by said control and sync transistors; said firstand second sections of said multi-section conductive carrier beingelectrically connected only through a mounting surface attached to saidpower semiconductor package.
 2. The power semiconductor package of claim1, wherein said control transistor and said sync transistor form a powerswitching stage of a voltage converter.
 3. The power semiconductorpackage of claim 1, wherein said multi-section conductive carrier ismade from a patterned lead frame.
 4. The power semiconductor package ofclaim 1, wherein said control transistor is a control FET, and saidcontrol transistor terminal is a drain of said control FET.
 5. The powersemiconductor package of claim 1, wherein said control transistor is acontrol FET, and said control transistor terminal is a source of saidcontrol FET.
 6. The power semiconductor package of claim 1, wherein saidsync transistor is a sync FET, and said sync transistor terminal is adrain of said sync FET.
 7. The power semiconductor package of claim 1,wherein said sync transistor is a sync FET, and said sync transistorterminal is a source of said sync FET.
 8. The power semiconductorpackage of claim 1, wherein said control transistor is a control FET,and said sync transistor is a sync FET, and wherein a source of saidcontrol FET is coupled to a drain of said sync FET through a switch nodesection of said multi-section conductive carrier.
 9. The powersemiconductor package of claim 1, further comprising a patterneddielectric situated between a plurality of sections of saidmulti-section conductive carrier.
 10. The power semiconductor package ofclaim 1, further comprising an insulator layer overlying saidmulti-section conductive carrier.
 11. The power semiconductor package ofclaim 1, wherein said mounting surface is a printed circuit board (PCB).12. The power semiconductor package of claim 1, wherein said powersemiconductor package is attached to said mounting surface by solderbodies.
 13. A method for fabricating a power semiconductor packagecomprising: providing a non-contiguous, multi-section conductivecarrier; attaching a control FET and a sync FET to said multi-sectionconductive carrier; forming a dielectric layer over said multi-sectionconductive carrier and said control FET and sync FET; patterning saiddielectric layer to form a patterned dielectric situated between aplurality of sections of said multi-section conductive carrier;fabricating conductive layers of said multi-section conductive carrierover said patterned dielectric and said control FET and said sync FET.14. The method of claim 13 further comprising forming an insulator layerafter said fabricating said conductive layers.
 15. The method of claim13, wherein said control FET and said sync FET form a power switchingstage of a voltage converter.
 16. The method of claim 13, wherein saidmulti-section conductive carrier is made by patterning a lead frame. 17.A power semiconductor package comprising: a non-contiguous,multi-section conductive carrier; a control transistor with a controltransistor terminal coupled to a first section of said multi-sectionconductive carrier; a sync transistor with a sync transistor terminalcoupled to a second section of said multi-section conductive carrier; adriver IC coupled to a third section of said multi-section conductivecarrier; said first, second, and third sections of said multi-sectionconductive carrier sinking heat generated by said control and synctransistors; said first, second, and third sections of saidmulti-section conductive carrier being electrically connected onlythrough a mounting surface attached to said power semiconductor package.18. The power semiconductor package of claim 17, wherein said controltransistor and said sync transistor form a power switching stage of avoltage converter.
 19. The power semiconductor package of claim 17,wherein said multi-section conductive carrier is made from a patternedlead frame.
 20. The power semiconductor package of claim 17, whereinsaid control transistor is a control FET, and said sync transistor is async FET, and wherein a source of said control FET is coupled to a drainof said sync FET through a switch node section of said multi-sectionconductive carrier.